Flexible lampholder

ABSTRACT

An improved method and apparatus for providing a sealed lamp and thermoplastic lampholder for an appliance (for example in a refrigerator) is disclosed which employs a low heat conductivity moisture seal between the lamp envelope and the lampholder in conjunction with an integral insulating flap or barrier which separates the external lampholder terminals allowing those terminals to be first individually connected to leads from a source of electrical energy and then encapsulated in an insulating medium without the danger that the terminals may become inadvertently shorted during the connecting and encapsulating process.

United States Patent 1 Kitt [ Apr. 17, 1973 [54] FLEXIBLE LAMPHOLDER [75] Inventor: Robert Alvin Kitt, Albion, Ind.

[73] Assignee: Lyall Electric, Inc., Albion, lnd.

[22] Filed: Aug. 3, 1971 [21] Appl. No.: 168,578

[52] US. Cl. ..339/60 R, 339/94 L, 339/128 [51] Int. Cl. ..l-l0lr 13/52 [58] Field of Search ..339/59-6l, 94, 126, 128

[56] References Cited UNITED STATES PATENTS 2,968,783 l/l961 Puetz ..339/59 L 2,725,546 ll/l955 Moore et al. ..339/60 R 2,694,798 11/1954 Cole ..339/126 R 2,151,882 3/1939 Woodhead.... ..339/60 R 3,233,033 2/1966 Mitchell ....339/59 L 3,359,527 12/1967 Hart ..339/59 L 3,559,153 l/l97l Cartelli ..339/59 L Primary Examiner-Joseph H. McGlynn Attorney-Jeffers & Rickert [5 7] ABSTRACT An improved method and apparatus for providing a sealed lamp and thermoplastic lampholder for an appliance (for example in a refrigerator) is disclosed which employs a low heat conductivity moisture seal between the lamp envelope and the lampholder in conjunction with an integral insulating flap or barrier which separates the external lampholder terminals allowing those terminals to be first individually connected to leads from a source of electrical energy and then encapsulated in an insulating medium without the danger that the terminals may become inadvertently shorted during the connecting and encapsulating process.

4 Claims, 6 Drawing Figures PATENTED APR 1 71975 SHEET 1 0F 2 FIIG.I

FIG,5

\NvENToR QoBERT ALVIN KYTT PAIENIEU 3,728,663

SHEET 2 OF 2 lNvENToR ROBERT ALVlN Km" k JQH'QrS Qmkert- FLEXIBLE LAMPHOLDER BACKGROUND OF THE INVENTION This invention relates to electric sockets or lampholders and more especially to lam'pholders of the variety typically found inside the normal home refrigerator. The relative humidity within a refrigerator may run quite high and condensation often as frost is the rule rather than the exception. ln such an environment, it is essential that the electrically conductive portions of the lamp base as well as the lampholder are well sealed so as to prevent a short due to moisture within the lampholder. Also, the recently instituted sponge test" by Underwriters Laboratories requires a positive moisture seal between the bulb envelope and the lampholder. It is known in the prior art to mold as an integral unit the insulative portion of the lampholder with a flexible lip which is slightly stretched when the bulb is inserted so as to form a moisture seal with the bulb envelope, however, these prior art seals have not been particularly effective especially when attempting to use thermoplastic materials such as polyvinyl chloride for the insulating portion of the lampholder and when using light bulbs which put out appreciable heat such for example, as the present commonly used 40 watt heavy duty appliance bulb. This 40 watt appliance bulb has a reduced envelope size which causes the temperature of the envelope to run as high as 101 C. The polyvinyl chloride material of which it is desired to construct the lampholder will lose necessary physical properties at this temperature and the prior art sealing lips fail standard tests under these circumstances within a 24 hour period.

Lampholders of this type are typically mounted by passing them part way through an aperture in a partition such for example, as the refrigerator wall so that the lamp is located on one side of the partition and the terminals or leads which are to be connected to a source of electrical energy are on the other side of the partition. One particularly interesting prior art procedure for completing the installation of such a lampholder consists of connecting two leads to the pair of terminals found on the lampholder and then encapsulating this pair of connections so as to insulate all exposed electrical conductors using foam-in-place insulation. Such a procedure often results in the clips or connectors as well as the terminals on the lampholder being distorted or displaced so as to come into contact with one another and the prior art procedures of foamin-place insulation have required that the connectors either be a single multiconductor type connector or that the individual connectors be provided with insulating sleeves. Such insulating sleeves or multiconductor connectors of course increase the cost of the resulting product.

SUMMARY OF THE INVENTION The above noted prior art defects are solved in accordance with the teachings of the present invention by providing a moisture seal between the bulb envelope and the lampholder having a substantially decreased area of intimate contact coupled with a larger area of no contact between the bulb and the lampholder so as to form an insulative airspace. The prior art problems associated with foam in place insulation are solved by providing an outwardly extending flap integral with the lampholder which lies between the two exposed external terminals. Individual leads having uninsulated clips or connectors are connected to these external terminals and the foam-in-place insulation is introduced and even though the terminals or connectors may move during the insertion or curing of the insulation, no shorts will occur since the outwardly extending flap al' ways lies between the two terminals despite any distortion they may experience.

Accordingly, it is one object of the present invention to provide an improved moisture seal between a light bulb and a lampholder.

It is another object of the present invention to provide an insulating strip which always insures that two terminals will not become shorted despite their being distorted during an assembly process.

It is a further object of the present invention to provide a thermoplastic lampholder which may be used in conjunction with a 40 watt appliance bulb and still meet industry safety standards.

A still further object of the present invention is to provide a more economical lampholder for a refrigerator.

Yet another object of the present invention is to provide an economical moisture impervious lampholder.

These and other objects and advantages of the present invention will appear more clearly from the following detailed disclosure read in conjunction with the accompanying drawings in which:

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a side view of a lampholder made in accordance with the teachings of the present invention;

FIG. 2 is another view of the same lampholder;

FIG. 3 is a perspective view of the same lampholder illustrating the manner in which conductive leads are fastened to the exterior terminals of the lampholder of FIGS. 1 and 2;

FIG. 4 is a more detailed view partially in section illustrating the external leads connected to the lampholder and showing the encapsulating insulating material;

FIG. 5 is a side view partially in section showing the lampholder of FIGS. 1 through 4 in position in a partition with its bulb in place; and

FIG. 6 is a sectional view of the lampholder in the same plane as illustrated in FIGS. 1 and 5 DESCRIPTION OF THE PREFERRED EMBODIMENT Consider first FIG. 5 which illustrates a lamp or bulb 11 having an envelope or globe 13 made of glass or other light passing medium, which bulb has its threaded base screwed into a screw shell within the lampholder 15. Typically of course, the base of the lamp has two terminals, one of which is the threaded portion which connects to the screw shell or other base accepting connector for example, as used with bayonet type lamps and the other of which is a centrally disposed contact which will mate with a corresponding contact in the lampholder. FIG. 5 illustrates the lampholder 15 as passing through an aperture in a partition 17 which, for example, may be a refrigerator wall. The lampholder is of course, partially on each side of the wall 17 so that the lamp 11 will be on one side of the partition while the external terminals 19 and 21 will lie on the other side of the partition. In the case of a refrigerator, the terminals 19 and 21 would be located between the interior wall 17 and an exterior wall not shown so as to be in the region of the thermal insulating material of the refrigerator whereas the bulb 11 would be interior to the refrigerator for obvious lighting purposes.

Comparing -FIGS. 5 and 6 it should be noted that the lamp 11 is not shown in FIG. 6 nor is the partition 17, however, the grooves which held the lampholder 15 in the partition 17 are illustrated as 23. Thus, FIG. 6 is a sectional view of the lampholder 15 only of FIG. 5. In FIG. 6, it can be clearly seen that the first exterior terminal 21 makes electrical connection with the threaded screw shell 25 which in turn of course forms one of the contacts for the lamp 11. The second external terminal 19 forms the second contact for the lamp 11 in the form of a centrally disposed internal contact at 27. The lamp is inserted into the holder of FIG. 6 from the left and it should be noted that at the very beginning of this lamp opening there is an annular constriction or lamp grasping portion .29 which is of a lesser diameter than the glass envelope of the lamp 11 is at a similar point and thus when the lamp 1] is inserted into the screw shell a portion of its envelope will expand slightly the annular constriction 29 so as to form a moisture seal between the envelope and the lampholder. Immediately adjacent to this annular constriction is an annular recessed portion 31 which has a diameter greater than the corresponding part of the lamp so as to form an annular airspace which airspace is exposed to the surface of the lamp for a greater axial distance than the axial dimension of the contact between the constriction 29 and the lamp. This airspace effectively defeats heat transfer .from the lamp to the lampholder by conduction thus effectively lowering the temperature of the moisture seal portion of the lampholder during operation and preventing deterioration of the seal. The airspace represented by the recess 31 has allowed lampholders made in accordance with the present invention of a polyvinyl chloride material to meet indus try safety requirements whereas lampholders not having this recess 31 have failed to meet such industry standards. The annulus of contact between the lamp 11 and the constriction 29 and the corresponding annular airspace should now be readily discernable in FIG. 5. Thus, the screw shell 25, the annular recess 31 and the annular constriction 29 are all coaxial with the recess and constriction being displaced axially from the screw shell.

Also illustrated in FIG. 6 is an outwardly extending flap 33 which is molded as an integral part of the insulating body 35 which is as noted earlier an insulating material of a thermoplastic nature and preferably a polyvinyl chloride. It should be noted in FIG. 6 that if one were to imaginarily bend the two terminals 19 and 21 toward one another the flap 33 would extendjust far enough out between these two terminals to prevent their coming into direct contact. As seen in FIG. 2, the flap 33 is also slightly wider and longer than the two terminals 19 and 21 so as to prevent not only the terminals from coming in contact with one another but to prevent clips or connectors such as 37 and 39 of FIGS. 3 and 4 from contacting one another.

As noted earlier, a desirable and economical system for insulating the external terminals of a lampholder such, for example, as insulating them in their location between refrigerator walls is to employ so called foam-in-place insulation which may be literally squirted into an inaccessible location and which on cur ing expands and forms a very fine insulated encapsulation of the terminals involved. Also as noted earlier, this type of insulating procedure causes some distortion to the terminals involved during the expansion of the material. To overcome this initial shorting problem the prior art has resorted to providing sleeves for the clips or connectors 37 and 39 illustrated in FIG. 4 or'to using a single multiple conductor connector which of course maintains the relative spacing between the several conductors. In contradistinction, the present invention contemplates providing a single flap 33 which extends outwardly from the lampholder between the two external terminals (seen more readily in FIG. 1) so as to prevent those two terminals 19 and 21 or their associated connectors 37 and 39 from coming into contact with one another regardless of the distortion experience by the terminals either due to the insulating process or the inadvertent application of undue tension to one of the leads 41 or 43. These leads, of course, are connected to a source of electrical energy for energizing the bulb.

The entire process of installing the lampholder of the present invention should be clear in light of the foregoing discussion. The lampholder itself illustrated in FIGS. 1, 2 and 6 which is the result of a previous integral molding process is passed partially through an aperture in a partition 17 of 'FIG. 5 and is retained there by the interaction of the partition and a mounting groove 23. Leads 41 and 43 which are connected to a source of electrical energy and having uninsulated clips or connectors 37 and 39 are pushed onto the external terminals 19 and 21. Next a foam insulating material 45 of FIG. 4 or any other thermal insulating material is applied so as to provide thermal insulation for the refrigerated chamber. Lastly, the lamp 11 is screwed into the screw shell 25 or otherwise inserted into the base accepting connector so as to both make its two connections within the lampholder and to expand the annular constriction 29 and form a moisture seal between the lamp and the lampholder; All of'the conductive surfaces associated with the lampholder are now completely insulated.

While the present invention has been described with reference to a specific embodiment, numerous modifications will suggest themselves to those of ordinaryskill in the art and accordingly the scope of the present invention is to be measured only by that of the appended claims.

I claim:

I. In a lampholder having a screw shell for accepting the threaded base of a lamp and connected to a firstex ternal terminal, and a centrally disposed contact for contacting said lamp base and connected to a second external terminal, an improvedmethod of sealing :said lampholder to prevent exposure of its electrically conductive portions to the environment comprising the steps of:

providing an annular constricted portion and an annular recess portion as integral parts of said of connecting comprises providing a pair of electrical lampholder coaxial with and displaced axially from said screw shell, the axial dimension of said annular recessed portion exceeding the axial dimension of said annular constricted portion;

providing an insulating barrier integral with said 5 lampholder and lying between said first and second external terminals of a size and configuration such that deformation of said external terminals toward one another cannot result in said terminals becoming inadvertently electrically in terconnected;

Passing the said lampholder part way through an aperture in a partition so that both said external terminals lie on one side of the partition, and the annular constricted portion and annular recess portion lie on the other side of said partition;

connecting the two said terminals to a source of electrical energy;

encapsulating at least both said external terminals and said insulating barrier in an insulating material; and

inserting a lamp in said lampholder so as to deform radially outwardly said annular constricted portion and thereby form a moisture seal between said lampholder and the envelope of said lamp and also form an annular airspace coaxial with and between said screw shell and said annular constricted position.

2. The improved method of claim 1 wherein the step leads each coupled to a source of electrical energy at one end and having an uninsulated connecting clip at the other end thereof and pushing the connecting clips onto respective ones of the external terminals of the lampholder whereby electrical separation of the clips prior to encapsulation is provided by the insulating barrier with subsequent electrical separation being maintained by the encapsulating insulating material.

3. The improved method of claim 1 wherein the annular constricted portion and annular recessed portion are molded of polyvinyl chloride, the step of inserting comprising moving the lamp sufficiently far into the lampholder to ensure that the constricted portion contacts only the lamp envelope along a narrow band to thereby keep the rate of heat transfer from the lamp to the lampholder below a level which is detrimental to the polyvinyl chloride.

4. The improved method of claim 3 wherein the step of connecting comprises providing a pair of electrical leads each coupled to a source of electrical energy at one end and each having an uninsulated connecting clip at the other end thereof and pushing the connecting clips onto respective ones of the external terminals of the lampholder, said encapsulating step comprising a foam-in-place process whereby electrical separation of the clips prior to encapsulation is provided by the insulating barrier with subsequent electrical separation being maintained by the foam insulating material. 

1. In a lampholder having a screw shell for accepting the threaded base of a lamp and connected to a first external terminal, and a centrally disposed contact for contacting said lamp base and connected to a second external terminal, an improved method of sealing said lampholder to prevent exposure of its electrically conductive portions to the environment comprising the steps of: providing an annular constricted portion and an annular recess portion as integral parts of said lampholder coaxial with and displaced axially from said screw shell, the axial dimension of said annular recessed portion exceeding the axial dimension of said annular constricted portion; providing an insulating barrier integral with said lampholder and lying between said first and second external terminals of a size and configuration such that deformation of said external terminals toward one another cannot result in said terminals becoming inadvertently electrically interconnected; Passing the said lampholder part way through an aperture in a partition so that both said external terminals lie on one side of the partition, and the annular constricted portion and annular recess portion lie on the other side of said partition; connecting the two said terminals to a source of electrical energy; encapsulating at least both said external terminals and said insulating barrier in an insulating material; and inserting a lamp in said lampholder so as to deform radially outwardly said annular constricted portion and thereby form a moisture seal between said lampholder and the envelope of said lamp and also form an annular airspace coaxial with and between said screw shell and said annular constricted position.
 2. The improved method of claim 1 wherein the step of connecting comprises providing a pair of electrical leads each coupled to a source of electrical energy at one end and having an uninsulated connecting clip at the other end thereof and pushing the connecting clips onto respective ones of the external terminals of the lampholder whereby electrical separation of the clips prior to encapsulation is provided by the Insulating barrier with subsequent electrical separation being maintained by the encapsulating insulating material.
 3. The improved method of claim 1 wherein the annular constricted portion and annular recessed portion are molded of polyvinyl chloride, the step of inserting comprising moving the lamp sufficiently far into the lampholder to ensure that the constricted portion contacts only the lamp envelope along a narrow band to thereby keep the rate of heat transfer from the lamp to the lampholder below a level which is detrimental to the polyvinyl chloride.
 4. The improved method of claim 3 wherein the step of connecting comprises providing a pair of electrical leads each coupled to a source of electrical energy at one end and each having an uninsulated connecting clip at the other end thereof and pushing the connecting clips onto respective ones of the external terminals of the lampholder, said encapsulating step comprising a ''''foam-in-place'''' process whereby electrical separation of the clips prior to encapsulation is provided by the insulating barrier with subsequent electrical separation being maintained by the foam insulating material. 